If p+q+r = 7, find the minimum possible value of p^2 + 9(q^2) + 4(r^2)?

41.
According to the question p+q+r=7 can be achieved by adding 1,2,4 only. There are 6 way you can write 1,2,4
(1+2+4)
(4+1+2)
(2+4+1)
(2+1+4)
(4+2+1)
(1+4+2)
By putting value (4+1+2) gives minimum value of 41